It is highly desirable in some situations to monitor the degree of wear of machinery so as to not only maximize human safety by forestalling failure but also minimize downtime and its associated expense and inconvenience.
It is well known that most industrial and propulsion machinery utilize ferromagnetic components which, when subjected to wear during operation, produce ferromagnetic particulate wear debris which becomes entrained in the machinery lubricating fluid and that as components in the machinery age both the concentration and size of wear debris particles increase. These concepts form the basis of tests which have been developed for monitoring the degree of wear in machinery. A well known method of wear detection by the monitoring of wear debris in oil samples periodically removed from machinery is known as the "Spectrometric Oil Analysis Program" (SOAP). Another method involves the installation of easily removable magnetic plugs in the equipment. The plugs attract and accumulate ferrous wear debris produced during the course of operation of the machinery. The plugs are removed periodically and examined for wear debris accumulation.
The principal limitation of these and other known wear debris detection methods and apparatus is that they are incapable of sensing or quantitatively monitoring wear in machinery on a real time basis. In most cases, the machine must be shut down and samples must be taken and analysed before an indication of the condition of the machine can be obtained.